A transient outward rectification in the cat sympathetic preganglionic neuron.

Intracellular recordings were made from sympathetic preganglionic neurons of the intermediolateral nucleus, in the slice of the T3 segment of the cat spinal cord. Depolarization to -60 mV from membrane potentials more negative than -75 to -80 mV caused a transient outward rectification which decayed in 0.5-2.0s. The rectification was sensitive to changes in K concentration, was abolished by 4AP (2 mM), and was unaffected by low Ca (0.25 mM), Co (2 mM), Ba (1 mM), TEA (20 mM) or intracellular Cs. These properties suggest that the rectification is due to a transient K-current similar to the A-current described in other neurons.